1. Field of the Invention
This invention relates to a power supply control device that controls a power supply of an external device, and to an image forming apparatus, such as a printer, a digital copier, a facsimile machine, etc., which includes the power supply control device.
2. Description of the Related Art
In most electric equipment including image forming apparatuses, some circuitry is kept running in a “standby” state in which the main power supply is on even while the electrical equipment is not being used. Meanwhile, when set to a Plug-in state in which an AC plug is inserted into a commercial power supply outlet and the main power is turned off, or set to a Plug-off state in which the AC plug is not inserted into the commercial power supply, operating instructions from a remote user cannot be accepted, although, it is possible to achieve power consumption lower than that in the standby state.
However, in such conventional electrical equipment, even if it is clear that the user does not use the equipment for a long period of time, for example, at night or on holidays, often the standby state is maintained continuously without pulling out the AC plug and turning off the main power supply in order to omit a turn-off operation and a turn-on operation to turn on the main power supply which the user performs at the next operation. Accordingly, there is a problem that more power than that in the Plug-off and Plug-in states is consumed.
To solve the problem described above, a technology to reduce the power consumption from the commercial power supply is already known in which a necessary operating power is supplied from a solar cell to receive the remote operation from the user continuously. For example, JP 2002-063011A discloses a device which supplies power generated by a solar cell to a printer in an energy-saving mode to reduce the standby power consumption so as to reduce total power consumption from the commercial power supply.
However, in the device disclosed in JP 2002-063011A which supplies an operation power at the energy-saving mode from the solar cell to reduce the power consumption from the commercial power supply, it is needed to generate sufficient power under a low lighting intensity environment by an indoor artificial lighting. Accordingly, it requires use of a large solar cell, which increases both the size and the cost of the apparatus.